154 ARTIFICIAL FORMATION OF WOODS. 



The above rule is subject to exceptions, because some seeds 

 will keep in good condition only for a very short period, or 

 their preservation involves much trouble and expense. The 

 seed of the elm ripens, on an average, at the end of May or 

 in the early part of June, and loses its germinating power 

 very rapidly ; hence it should be sown at once. Birch seed 

 also should be sown as soon as it ripens, about the beginning 

 of August. The seed of silver fir ripens in autumn, and, as 

 it does not keep well, it should be sown at once, and not kept 

 till spring. Many foresters prefer sowing heavy seeds, like 

 those of oak, beech and sweet chestnut, in autumn, because 

 they are bulky and it is expensive to keep them in good 

 condition over winter. At the same time these heavy seeds 

 are much exposed to attacks by animals during winter, and 

 as autumnal sowings germinate early in spring the seedlings 

 are exposed to late frosts ; hence, sowing them in autumn may 

 be of doubtful expediency. 



In some cases autumn sowings are indicated in localities 

 which are not accessible until late in spring, such as high 

 altitudes where snow does not disappear before June. Again, 

 alder seed is frequently sown in winter, immediately after 

 harvesting, as it is difficult to keep until spring. 



To sum up, it maybe said that in' temperate Europe spring 

 sowing should be the rule, but that certain species and certain 

 local conditions demand exceptional treatment. 



In other parts of the world, under different climatic con- 

 ditions, the best time for sowing also varies according to 

 circumstances. In the Indian plains and low hills the 

 general rule is to sow at the commencement of the summer 

 rains, because the seeds will then be assured of a sufticient 

 supply of moisture, and the seedlings will have time to 

 establish themselves thoroughly in the ground, before the 

 next dry season comes round. Sowings on irrigated lands 

 can be made at other seasons. The seed of some Indian 

 species does not keep, and indeed the seed of Sal {Sliorm 

 robusta) often germinates before it falls, and must therefore 



